Fastening approximately cylindrical erasers to one end of a pencil by means of a relatively thin-walled metal sheath, generally called a capsule, has been known for many decades. The sheath is mounted onto one end of the pencil, the pencil usually having been somewhat compressed beforehand in this area, so that the sheath is already held somewhat in place on the pencil, although not firmly. A cylindrical eraser is then inserted into the open end of the sheath. This manner of preassembling the pencil, sheath and eraser is presumed in the context of the present invention and will not be altered. The sheath is then deformed relative to the pencil on the one hand and the eraser on the other. To this end, tongs having a plurality of tips engage the sheath in the vicinity of the pencil and press inward on the sheath at a plurality of points, causing it to mesh with the pencil. In the same manner, the sheath is deformed by means of the tongs in the vicinity of the eraser, so that again a connection is established between the sheath and the eraser. This mode of operation can only take place in increments, because the pencils are moved individually toward the tongs. The sheath is deformed while the pencils are at a standstill. Such an operation is expensive in terms of machinery and does not permit high-speed operation.